thomas



w v. TURNER AND T. H. THOMAS. REGENERATIVE BRAKING SYSTEM FOR SERIES MOTORS.

APPHCATIQN FILED SEPT. 6, I916- Patented Nov. 25, 1919.

2 SHEETS-SHEEI 1- W. V. TURNER AND T H. THOMAS.

- REGENERATIVE BRAKING SYSTEM FOR SERIES MOTORS.

APPLICATION FILED SEPT. 6. I916.

Patented Nov. 25, 1919.

2 SHEETSSHEE[ 2.

- FIG. 2.-

l mi 1 l in our prior'application Serial No. 76,237,

. STATES PATENT OFFICE.

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7 Be it known that we,'W;\-L'rnn V. and THOMAS H. THOMAS, citizens-of. the

United; States, residing at, respectively, Winkinsburg and Edgewood,lin the countyof Allegheny and State of Pennsylvani -have jolntly' invented a certain new an 7 useful Improvement in Ree'nerative Brak,

direct current is employed for propelling the vehicles, such as shown and describe filed February 5, 1916. ln said prior application, the improvement 1s shown asapplied to a four motor car equipment,1n which the field coils of the motors may be 1 connected in parallel for series excitation;

in propelling the car, and connected in se-- ries and supplied with current from the line whenoperating as generators in regenerative braking. The reason for this special arrangement is that the field resistance fora series motor is so low-that, if the fields be left in parallel when regenerative braking is started, the amount of current flowing through themwould be prohibitive. .As the fields of these special motors are of a higher resistance than usual, in ordervto keep down the current while regeneratin from line excitation, it is necessary to shi J from a series to a parallel connection when propelling the car.

The object of provide means whereby the usual form of series-wound motor may .be employed, and it provides that the motor field of the usual low resistance shall be permanently connected in series with the motor armature, which is the usual arrangementfor a railway motor, and thereby-make it unnecessary to use a separate supply of current from the line to energize the fields in re generative braking.

According to another feature of our improvement, the circuit between the motors acting as generators and the line is not connected when electro dynamic braking is first started, but the circuit is closed through a resistance; then as the voltage is built nip el '5 :fr the re i u l magne i m of the fi 1 Specification of Letters l'atent. Application-filed wants a, 1916, ser al no. naeoa.

circuit in the three different 1 closed our present invention is to nncmmrrvn rmxme srsrmitroa "seams Morons.

Patented Nov. 1919.-

toapoint greater than that ofthe line the '2, a sectional diagrammatlc view showing the controller valve and fluid pressure actuated switch on a larger scale; Figs. 3, 4 and 5, circuit diagrams illustrating the course of the current in the regenerative V positions of the 1automatic series-parallel switch, respective y. y

We will first describe the ap aratus in so far as thesame corresponds with that of our rior application above referred to.

' T e electric connections, including the circuits, controllers, switches, etc., for con- 'trolllng' the motors in propelling the vehicle, are not shown in the drawing, and only a sufficient number of contacts representing a brake switch or controller, 2, are shown connected to the local or regenerative circuits of the generators as are necessary to illustrate the operations during the regenerative braking'periods. The contacts of the brake switch, 2- are indicated in the osition, that is the position to which t is switch is moved to open the propelling'circuits and connect up the motors to act as generators inwthe regenerative cir cuit for braking purposes and for restoring energy to the ne.

It will be understood that the contacts for the brake switch, 2, may be mounted j upon or operated by the running controller or master controller when turned to a cernected into the propelling system of the mo tors.

In the drawing, we have illustrated, dia grammatically, a four motor equipment, comprising standard series-wound motors having armatures A, A" A and A, com

tions in the speed of the vehicle, the means,

a1 goverrlven i the fluid of each motor when in brakingsition.

The change over switch, 3, may 0 rated by various forms of speed contro led means which serve to shift the relation of the generators according to certain variaas shown, comprising a centrif nor, 3, the shaft of which may froman axle of the vehicle and operate through lever 6, to open and close the valves, 6 and 6", for controlling the supply-- of fluid to and exhaust from the pistons, 7.

. and 7", of cylinder, 7. A partition, 7"," divides the cylinder into separate chambers,

for the respective pistons, the piston, 7, being connected toactuate the switch, and having a spring 7 opposing the action of ressure.

When is e vehicle is traveling at or above a certain speed, at which the governor raises the lever, 6, to close the exhaust and open both valves, 6' 'and.6", to admit fluid to'both pistons, 7 and 7", the switch, 3, is held in full parallel position as shown in the drawing. When the speed diminishes sufliciently to close one valve, 6, and open the exhaust from piston, 7, the sprinfi, 7, shifts the switch tov the series-para el position, at which point the piston, 7, engages piston, 7", and is held until the speed is further reduced sufiiciently for the governor to close valve, 6, and open the exhaust from piston, 7 whereupon the spring moves both pistons and the switch to the series position.

A booster, 4, is employed for raising the voltage of the current from the generators sufliclently above the line voltage to return current to the line, and .to maintain the regenerated voltage as the speed diminishes,

the booster being driven by a motor, 4, with current from the line through the wire, R,

leading from the regenerative braking switch 2. One of the armature terminals of the booster is connected to the return lead, H, from the generators, the other armature terminal being connected by wire, S, with the line, T, through a contact'bar on regenerative switch, 2. The field of the booster is energized by current from the line through wire, R, and may be controlled by a rheostat, 13, governed by the solenoid or magnet, 12, inserted in the regenerative circuit wire, S, whereby the strength of the booster field may be automatically adjusted by said nerated current to maintain a substantially constant current re ardlessof fluctuations in line voltage or ot er conditions which might vary the output of the generators. The booster is also governed by the speed of the. vehicle in order to compensate for the reduction in speed during the respective. periods that the motors are connected up m their difl'erent relations by the chan over switch, 3'. This may be convient y done by inserting a rheostat, 5, .in the field circuit of the motor, 4, the rheostat bein controlled by the speed vernor, 8. As 5 own in the drawing, a car is employed having a lever, 5, for exerting a varying pressure on the carbon disks to varythe resistance in the fields of the motor, 4. A spring, 8", acts upon lever, 5, tending to diminish the pressure upon the carbon rheostat, and thereby increase the resistance, the force of the spring, 8", be' regulated by the movement of the weights 0 the overnor,:3. Another spring, 8, acts on the ever, 5, in the opposite direction and tends to. increase the pressure on the carbon rheostat. The effective pressure acting on the rheostat is, therefore, the difierenoe between the force of the springs, 8" and 8, and

as the shifting of the governor weights, due to variation in speed, also varies the force of the spring, 3", the'resistance of the rheostat, and consequently the speed of the motor, 4,

n rheostat is acoordin lyregulated to compensate'for the diminis ing speed of. the motor generators. In order to continue this regulation through'each period of regeneration for'the difl'erent positions of the change over switch, 3, other springs, 8 and 8, are mounted to act on the lever, 5, but are held out of operation by means of the pistons, 8 and 8", when the change over switch is in full parallel position, the valves, 6" and 6", also controllxizpfi these pistons. on these valves are operated by.the governor, to release fluid from the pistons, 7 and 7", fluid is alsoreleased from pistons, 8' and 8", thus throwing the springs, 8 and 8', onto the force of the lever, 5.

The coil of the magnet valve, 9, is inserted in the return wire, so that when the speed of the vehicle and the corresponding regenerated current has diminished, to a predetermined low amount, this valve is automatically opened to vent air from a ipe of the air brake system, and cause an app icatior of the air brakes to complete the stop. Another vent valve, 10, is arranged to be operated to likewise vent air from the pipe of the air brake system when the speed of the vehicle exceeds a predetermined maximum the supply of fluid to adjusted to any point desired by means of the hand lever device, 11, connected to shift .the fulcrum of lever, 10. It is preferred that this device be so adjusted as to cause an automatic application of the air brakes switch is turned'to the running p.os'ition,1 and opened when [the break switch is throw-11 to the position shown in the drawing for establishing the regenerative circuits. For thepurpos'e, of cutting oi the regener-Y ative circuits. when thespeed of the vehicle.

has reduced" to the -minimunnat which the vent valv, 9, is open inserted in the return wire, H, from the generators, theswitch'bein held closed by 18, from the pig tem when the rake switch, 2,,and va1ve,-

piston,i1'0 and airadmitte ;through valve,

e, 15, of the air brake sys- -l8,i "are,turned to the position shown. When the vent valve, 9, is opened, it also releases the air pressure from piston, 10",'and the spring, 10, then automatically'opensthe' circuit, H, The maximum speed, vent valve,

10, is,-however,' preferably so connected as I to reduce, the air pressure for causing an application of the air brakes, but not to release the pressure from piston, 10.- The "switch, 10, thus remains closed. at that time "so that'the combined brakingefl'ect from-thev I regenerative system and theair brake" system is produced. As soon as the speed is-.'

reduced to the predetermined safe amount for which the apparatus is adjusted, the vent valve, 10, closes, and the air brakes are automatically released, thus limiting the speed of the vehicleduring the regenerative period.

When the brake switch is in running position, the vent valves, 9 and 10, are cut off from the ipe of the air brake system, by means of t e valve, 18, which turns. with the brake switch, but in braking osition, as shown, communication is estab ished from the pipe, 15, of the air brake system to both valves, 9, and 10, and also from the fluid pressure piston, 10", .to the vent valve, 9. The regenerative circuit switch, 10, is, therefore, normally held closed by the air pressure acting on piston, 10.

As thus, far described, he construction is similar to that of our priorapplication, except that the contacts on the controller, 2, are differently arranged to connect up the series-wound motors to act as generators in the regenerative braking circuit, and to build ed, a switch, 10, is.

up the field m ets from their residual I magnetism, as wi Ibo-readily understood.

According to another feature of our present improvement, the braking circuit is not a connected to the line until the voltage of the generated current is greater than the line voltage, and for this urpose an additional switch, 16, is provi ed-in the return wire, S, for controlling the connection to the line and for closin the braking circuit independently tll'lOlll a resistance. ing to the construction shown, this switch is provided with a contact bar adapted. in one position to connect the wire, S, to the wire, Z, leading through the coil, 9, of ma et valve,.9, to the contact baron the contro er,

.2, which is connected to the line T, and the wlre, R, in the braking position, as shown,

and in its other position to disconnect the wire, Z, and connect the wire, S, to the wire,-

U, and the ground through two parallel circuits, one including the heavy resistance, X, and the other the lower coil, 14, of themagnet. 'valve device, 14, which controls the supply and release of fluid under pressure toand from one of the actuating pistons, 16",

of the switch, 16. The upper coil, 14", 1s

. permanentlyenergized by current from the Accordline through abranch from wire, R, to

ground when the controller is in braking position. The supply of fluid to the other piston,.16", is controlledby the valve, 18.

The switch, 16, also carries a contact bar adapted in one position to close a connection from a branch of the wire, R, to the wire, Y, leading a through the coil, 9", of magnet valve, 9, toground; this being for the purose of holding 'valve, 9, closed when the rakingci-rcuitis closed and the connection I towire; the line through the coil, 9,

is.open'.=;- r

- ll'positions-except that of braking, the

air to the piston, 16, and opening the exreo I 13,. admits air under pressure to the. piston, 16 and'the valve device, 14, at this time is in position for closing the supply of haust therefromto the atmosphere, as neither of the coils, 14" or 14, is energized.

The switch, 16, therefore, normally occupies the position at the left in which the wire, Z, isdisconnected and the'wire, S, is connected to wire, U. The wire, R, is also electrically connected'to the wire, Y, and coil, 9", as shown in Fig. 2. I

When the controller, 2, is thrown to the braking position, the valve, 18, is turned so as to cut of! the supply of air to the piston, 16", and open the exhaust therefrom to the atmosphere. At the same time the motors are connected up to act as generators in the braking circuit, and connection is made from the line, T, to the wire, R, for operating the booster motor, 4', and for we 'zing the magnet coils, 14 and 9. The coi 14", then holds the valve, 14, in the same position and there is no movement of the switch 16, which still connects the wires, 8 and so that the local brake circuit of the nerators is closed through the resistance, and coil, 14, but is cut ofl' from the line. The magnet valve, 9, is, however, held closed by the energizing of the lower coil, 9", so that an undesired application of the air brakes is revented, while the brake circuit is cut oil rom the line and the up ma et coil, 9, consequently deenergiz As t e motors then be n to generate current, the change over switch, 3, will occupy one of its three positions according to the speed of the vehicle, as determined by the governor, 3, and the strength of the current generated will rapidly increase as the fields are built up from their residual ma of the current will be mm the motors, connected either in full parallel, seriesarallel or full series, by the return wire, H, t rough the booster, 4, wire, S, switch, 16, and wire, U, through resistance X, and ma et coil, 14, to ground and the return si e of the motors, as indicated in the dotted line sition of switch, 16, in Figs. 3, 4, and 5, As soon as the strength of the nerated current acting on the magnet 0011, 14, is 'suflicient to overcome the efl'ect of the line current acting on magnet coil, 14", the valve device, 14, will be automatically shifted to close the exhaust and admit air under pressure to piston, 16, to throw the switch, 16, to its op osite position. The im ressed voltage 0 the regenerated current is then sufiiciently eater than the line 'voltage, and the connection to the line is thus made by the movement of the switch, 16, as before described, that is, the wire, S, is connected to wire, Z, leadin through coil, 9, to contact bar on contro ler 2, and the line, T. At

- current will be the same time, the w1re, U, leading through and the wire, Y, leading through coil, 9", are cut out.

The further operation of the regenerative braking system in restoring energy to the line is substantially the same as that of our prior application that is, supposin the change over switch, 3, to be in its ful arallel position, as indicated, the course 0 the from one terminal of each of the generators, connected in parallel, to return wire, H, throu h armature of booster, 4, wire, S, magnet c011, 12, switch, 16, wire, Z, magnet coil, 9, contact bar on switch, 2, to line, T, and return by ground connection to the other terminal ofthe generators, as

indicated in diagram, Fig. 3.

If the regenerated current rises higher than a certain amount, the force of the magnetic pull of the core of the magnet, 12, acting on the lever, 12, will be increased and the pressure of spring, 12", on the carbon rheostat diminished, so that less current from the line will flow through the rheoetism. The course naaaeee stat and the fields of the booster, 4, will be correspondingly weakened, thus regulating the booster to decrease the amount of current flowing back to the line. This feature serves to keep the current flow properly balanced at all times. With the speed at the rate as above indicated the weights of the overnor, 8, move out radially to a position 1n which the lever, 6, clears the valves, 6 and 6, and a certaintension is exerted upon the spring, 3", and transmitted to the lever, 5, acting upon the carbon rheostat, 5. With the valves, 6 and 6", in the positions shown, the exhausts are closed, and fluid pressure is admitted to all of the pistons, 7", 8 and 8, thereby relieving the lever, 5, from the force of the springs, 8 and 8, so that the effective ressure 'actin on the carbon rheostat,-5, will be that whi is produced by springs, 8 and 8.

As the speed of the vehicle begins to diminish, due to the retarding efl'ect produced by the generators in regenerating current and resto same to the line circuit, the governor weights move inward, and there tend to increase the force of the spring, 8 This has the efiect of varying the pressure of lever, 5, upon the carbon rheostat, 6, and thereby regulating the motor, 4, driving the booster, 4, so as to compensate for the diminishing s ed of the vehicle and the generators, an maintain the voltage of the. regenerated current above that o the line circuit. As the speed continues to diminish, the further inward movement of the governor weights serves todepress the lever, 6, sufliciently to operate the valve, 6, to close its supply port and open its exhaust port, whereupon the fluid is released from pistons, 7 and 8. The spring, 7, then moves the piston, 7, downward against the stem of piston, 7", and throws the switch, 8, to its series-parallel position, whereby the volta generated will be increased, and there y compensate for the diminished speed of the vehic e. The course of the current in this'position of the switch is indicated in Fi 4. In order to make a corresponding infliction in the speed of the booster to maintain the voltage of the regenerated current substantially constant, the spring, 8", is released' and exerts its pressure on lever, 5, and rheostat, 5. The field of the motor, 4, is thereby strengthened and the speed of the booster reduced the desired amount. The current will then be restored to the line throughout another period of further reduction in the speed of the vehicle, during which the motor,'4, of the booster, by means of rheostat, 5, spring, 8" and governor, will be repeated as before escribed.

As the speed continues'to decrease, the vernor weights move farther inward, and

53 m, th lever, 6, to operate the valve 6,

period the regulation of name springs, 8 and 8 acting on the lever, 5',

thus again adjustingthe rheostat, 5, to reduce thespeed of the motor, 4, and booster,

A, to correspond with the changed relation of the generators.

The voltage of the regenerated current is thus maintained high enough to 'flowto the line circuit throughoutinearly thefull stop- Y ping eriod, but when'the speed is reduced tosuc a low rate that the current fails to hold the magnet valve,.9,. closed, this valve opens .to vent air from the pipe, 15, and effect an a plication of the air rakes 'to complete th sto' .The fluid will also be released from t e piston, 10", at the same time, and the s ring, 10, operates the switch, 10, to open the regenerative circuit to prevent back flow of current from the line.

If, at the time the brake switch is turned to braking position, the speed of the vehicle is in excess of the desired maximum, as

determined by'the adjustment of the device, 11, the vent valve, 10, will be immediately operated by the governor. to discharge air from the air brake system and efi'ect an application of the air brakes. The regenerative brakingefiect will also be obtained,

and the combined action of the two braking systems will soon reduce the speed to a safe amount.

- operate in perfect harmony. It is not possible for one system to oppose the other at any time or at any speed, and the air brake may be used to supplement the action of the regenerative brak ng system at'any time, as desired. Having now I claim as new and desire to secure by ters Patent is:

1. In a regenerative braking, system, the combination with a plurality of serieswound motors, of a brake switch having contacts for connecting one field lead and one armature lead of each motor, and other contacts for connecting the other field and armature terminals wlth a series parallel switch, and a series parallel'switch governed by the speed of'the vehicle for automatically shifting the relation of said motors.

described my invention, what Let- 2. In a regenerative brakin system, the combination with a plurality o motors, of a brake switch having contacts for connecting up the motors to act as generators in a loca brakingcircuit, a'switch for controlling'the.

connection between said bra circuit and the line, a fluid dpressure device or actuating said switch, an means governed by the Volt age of the braking circu t for controlling the fluid ressure. 1

3. n a regenerative brakin system, the combination with a plurality o motors, of a brake switchhaving contacts for connectin up the motors to act as generators in a loca braking circuit, a switch for controlling the connection between the brakin circuit and the line, means governed b .t 'e movement of the brake switch for shi ting said circuit switch to one position for cutting out the line connection, and means governed by the voltage of the braking circuit for shifting said switch to another position to close connection with the line.

4. In a regenerative brakin system, the

combination with a plurality o motors, of a brake switch having contacts for connecting,

up the motors to act as generators in a local braking circuit, and switch mechanism overned by the movement of the brake switch and by the voltage of the braking circuit for controllin the connection between said circuit and t e line.

5. In a regenerative braking system, the combination with a plurality of motors, of a brake switch having contacts for connecting u the motors to act as eneratorS in a local braking circuit, a switc for controlling the connection between-the ,brakv tomatically connecting the brakin circuit to the line whenthe voltage in sai circuit w rises above the line voltage, of an air brake system, a vent valve for effecting an application of the air brakes whenthe speed of the generators falls below a predetermined minimum,,a magnet coil for the vent valve energized by the current restored to the line, and means for holding said vent valve closed before the braking circuit is connected to the line.

7., In a regenerative braking system, the combination with a plurality of motors, a brake switch having contacts for connecting u the motors to act as generators in a local rakin circuit, and switchmechanism 'for automatically connecting said circuit to' the line when the voltage of 'said circuit exceedsthe line voltage, of an air brake system, a magnet valve controlled by the nerated current restored the line for e an ap lication of the-air brakes when t e speed of the regenerators falls 'below a predetermined amount, said valve also being controlled by current from the line while the braking circuit'is being built up to the line voltage.

8. -In a regenerative braking system, the

I combination with a-plurality of motors, a

brake switch having contacts for connect mg n the motors to act as nerators in a local raking circuit, and switch mechanism for automatically connecting said circuit to the line when the voltage of said circuit exceeds the line voltage, of an air brake system, a magnet valve controlled by the re-- a generated-current restored to the line for efiectin an ap lication of the air brakes when t e s (l of the regenerators falls below a pre ermined amount, and a magnet coil energized by. current from the line for holding said valveclosed when the generators are buildi .when t e spee up the current in the braking circuit an before the connection is made from said circuit to the line.

'9. In a regenerative braking system, the

tem, a magnet valve controlled by the regenerated current restored to the line for effect" an apfilication of. the-'air brakes of the regenerators falls below a redetermined amount, a magnet coil energized by current from the line for holding the valve closed, and means actuated by said switch mechanism .for cutt' off theline connection to said ma et coi WALTER V. NER. THOMAS H. THOMAS.- 

